Crops sold in the international market trade away the water they're grown with.
The connection between water supplies, food, and international trade is closer than you might think. Globally, 70 percent of freshwater is used for irrigated agriculture, and one source of that water is underground aquifers. Aquifers form when water accumulates in the ground over time, sometimes over hundreds or thousands of years. Some of these aquifers become depleted, meaning that they do not accumulate rainfall fast enough to replace what is drawn out to the surface, either naturally to lakes and rivers or in this case by people via pumping. Once that groundwater is depleted, it will effectively be gone for good on the scale of a human life-time, and will no longer be available for relief during emergencies such as droughts. University and NASA researchers have used computer models of groundwater depletion and irrigation and compared them to records of the international food trade. They've traced the connections between food grown with depleted groundwater to individual crop sectors, countries, and their trade partners in order to better understand how we might conserve our freshwater resources. Watch the video to learn more.